1. Field
Inventive concepts relate to a package-on-package assembly.
2. Related Art
One constant in the world of electronics is the demand for increased functional density: greater circuit capacity packed within ever-smaller volumes. One approach to achieving such miniaturization is a packaging technique referred to as “package-on-package,” which unites a plurality of semiconductor packages as one. As the capacities of the united packages increase, the interconnection requirements may increase and, in order to satisfy the need for greater interconnection capacity without increasing the volume of the package-on-package, individual interconnections are reduced in size. That is, finer-pitch interconnections may be employed to address the demands for a greater number of interconnections within a given space. However, as interconnection pitch is decreased, the area of contact, and resultant adhesive force, between the interconnection and packages' landing pads may be decreased. As a result, the security of the connections may be compromised and the compromised connections may lead to failure of the package-on-package system.
The adhesive force between the top package and the bottom package may be increased by using an additional adhesion member, thereby lessening the stress on the interconnection. A top solder ball attached to the top package and a bottom solder ball attached to the bottom may be adhered to each other to form an interconnection using a reflow process. However, if the top and bottom solder balls are smeared with adhesion member material during the reflow process, a wetting problem may be created for the top and bottom solder balls, thereby reducing the reliability of the interconnection.